Thanks for pointing out that 00 is equivalent to typing + in a SkypeOut dial string. Not only did I not know that, I couldn't find it documented anywhere in the Skype help files or documentation--though it is mentioned in plenty of other third-party documents (as for example at http://www.dontronics.com/phoneconnector.html
where you'll find this text "Skype will accept "00" as a substitute for the "+" character, so to dial a Skype Out, or real telephone number, you simply dial 00, then country code, then number.").
I'm going to have to let the guys at IOgear know about this, too, because they were no more aware of it than I was. Now, instead of adding a + button to their dial-pad, they need only add this information to their documentation. A much easier fix for them, which I'm sure they'll be glad to learn about, as I was.